Organisers of the Lausanne Diamond League meeting say United States sprinter Justin Gatlin has ended his season early because of illness.
Gatlin, the 100-metre bronze medallist at the London Olympics this month, was due to run at the Athletissima meet in Switzerland.
Gatlin was treated for stomach pains and fever at a hospital in Austria this week.
Athletissima organizers say in a statement that "his situation has not improved."
They say Gatlin "has taken the decision to return to the USA, withdrawing from the meeting in Lausanne as well as ending his season."
Gatlin was scheduled to face Olympic silver medallist Yohan Blake of Jamaica and American teammate Tyson Gay, who placed fourth in London.
Olympic champion Usain Bolt has opted to run the 200.
AP